The present invention pertains to the field of catheter-based delivery systems. Particularly, it relates to an intravascular apparatus for delivering pharmacological or biological materials. More particularly, it involves a deflectable injection catheter for introducing therapeutic agents, such as cell cultures, growth factors, angiogenic agents, and the like, from within a chamber of the heart into damaged myocardium.
Coronary disease is the most prevalent cause of death in the United States. A heart attack, or myocardial infarction, occurs when coronary artery blockages severely restrict or deprive the heart muscle of blood flow. Blood supply which is greatly reduced or blocked for more than a transitory period of time can result in a significant loss of functioning heart muscle. The heart muscle cells, or cardiomyocytes, that die following a heart attack cannot be replaced by the body under normal conditions, because heart muscle cells are incapable of effective regeneration after injury or infarction. Instead, as a result of the healing phase after a heart attack, a scar is formed in the affected region of the heart.
This fibrous scar tissue cannot contract, does not contribute to heart function, and causes the rest of the heart to work harder and overcompensate for the nonfunctioning portion. As the uninjured regions of the heart become overburdened, a progressive deterioration can occur culminating in congestive heart failure.
Treatment options for damaged heart muscle and resulting end-stage heart failure include drug therapy, revascularization of the damaged tissue, mechanical circulatory assist devices, ventriculotomy, and heart transplantation.
Drug therapy is precluded in a number of refractory patients, generally only treat symptoms and has a limited effect on the progression of the disease. Transplant is limited by a shortage of donor hearts and need for continuous immunosupression.
Moreover, most of the above approaches involve highly invasive surgical procedures, with cardioplegic arrest and cardiopulmonary bypass.
What is needed is a method and means for delivering therapeutic agents to such patients in a minimally invasive procedure. More preferably, the need exists for percutaneous, localized delivery of therapeutic and pharmacological agents.
Catheter systems have been proposed for myocardial revascularization, via drilling or boring channels in the myocardium, such as by laser or needle, and, possibly, deposition of angiogenic substances within the channels created as an adjunct thereto. Such devices, however, raise performance and safety issues.
Specifically, precise control of the depth of the channel into the myocardium so as not to pierce the epicardium. More specifically, prior deflectable injection catheters exhibit shrinkage in the catheter shaft due to compression thereof when the catheter is deflected. This can change the relative position of the needle and the catheter shaft leading to inaccurate readings on the depth of needle insertion into the tissue to be treated.
Also, without a retraction default mechanism such prior catheter systems can cause injury to the endocardium from the instruments used to drill or bore the channels, or during advancement and delivery to the target location from these instruments. Further, a catheter capable of accessing more difficult areas of the heart is advantageous to achieving full benefit of the procedure. Additionally, minimal resistance to the flow of the agents or materials being deposited is desirable.